Digital power conversion and digital power management were demonstrated during a special "Digital Power Supply Control" session at Techno Frontier. Cosel, Bellnix Co, Ltd., and TDK Lambda all made presentations about the benefits of digital power to improve performance and lower the cost of power converters.
Cosel used the just-released CHS series of regulated bus converters to demonstrate several benefits of digital control. These converters deliver 80W with 93% efficiency from a sixteenth-brick format and 200W with 94% efficiency from an eighth-brick format. These bus converters employ Cosel’s "digital assisted control" to combine the benefits of fast analog control with the flexibility and component count reduction enabled by microprocessor-based digital control.
As a result of employing digital control, the CHS series features a 15% reduction in components compared with the previous-generation CES family and a 4% increase in efficiency. In addition, the new units have a flatter efficiency curve for improved light-load operation. The new bus converters along with a family of point-of-load regulators (POLs) are being targeted at intermediate bus architecture (IBA) applications.
Next in the session, Bellnix demonstrated the performance of its 10A BDZ series POLs, "the world’s smallest" 10A units. The Bellnix POLs employ a microcontroller to deliver PMBus communications to both monitor the operating condition of the converters and to change the settings while the converter is in operation. These POLs deliver 94% efficiency when providing a 1.5Vdc output from a 12Vdc input. They measure 26.4mm long X 18.0mm wide X 8.5mm high.
In addition to demonstrating the benefits of digital power conversion and PMBus communications in IBA dc-dc converter applications during the digital power supply control session, TDK-Lambda was showing their digitally-controlled EFE-M series of 400W medical/ITE power supplies in their booth. With a 3.5 x 6.5 inch footprint and less than a 1U profile (1.34" to1.60") the EFE400M series includes an integrated magnetics transformer (transformer and inductor windings on the same core) to boost efficiency to typically 90% and employs an 8-bit microcontroller for full digital control of the output and to handle housekeeping routines. This resulted in a 25% parts count reduction to achieve a 45% smaller and up to 56% lighter design when compared to previous-generation products.
TDK-Lambda’s control of the EFE400M allows the power supply’s performance, such as current limit and start-up characteristics, to be optimized digitally – this feature eliminates the hardware changes usually required in analog designs. A reduced cost primary side control topology is employed, supervised by the microcontroller. This results in fewer parts and higher efficiency without sacrificing load regulation performance. Furthermore, the need for an opto-isolator is eliminated – a device which is undesirable for long life power supply designs.